Signal input and output unit



FIG. 1 is a perspective view of a signal input and output unit showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a right side view thereof, the left side view being a mirror image of the right side view. 

The ornamental design for a signal input and output unit, as shown and described. 